Burned out rear light cluster

[RayPooley]

Hello people

Got a burned out rear cluster connector. I think it's the power wire.

I have ordered a new bulb holder and terminal connector.

Does anyone know what might have caused this overload?

Anybody seen this problem themselves?

There doesn't seem to be anything obvious.

All opinions welcome.

 

[Blobcat]

Hello and welcome

High resistance is normally the result in high heat. It’s not uncommon unfortunately - there’s a few threads with similar issues, please have a search in this section of the forum.

 

[A.J.]

This is quite common problem on a W204. Corrosion is also a factor.

 

[arion]

Hello people

Got a burned out rear cluster connector. I think it's the power wire.

I have ordered a new bulb holder and terminal connector.

Does anyone know what might have caused this overload?

Anybody seen this problem themselves?

There doesn't seem to be anything obvious.

All opinions welcome.

This is a very common problem in these cars, the ground cable (brown/melted one) is too thin and it overheats over time.
Best solution to prevent this from happening again is using a thicker wire for the ground.
(One end goes to the connector and the other end to metal)

 

[RayPooley]

Thank guys. Good to know. especially the the heavier guage ground suggestion. I will implement that when the gear arrives.
Sorry for the delay in responding. The notifications were in my spam folder.

 

[RayPooley]

Hello people

Just thought I would give a little feedback for the benefit of those who have this issue.

The total draw on all of these bulbs if they were to be on simultaneously is 9.4A.
The 5 large bulbs draw 1.8A each an the 1 side lamp bulb draws 400mA.
So you're not going to have any issues with the individual lamp circuits from a current perspective.
But how likely is it, you might ask, you're going to have all of the lamps on at any given time?
Not likely.
So I don't think it's necessarily a matter of under spec cable for the ground wire.
It's not like all these cars have this problem.
If it was you would expect the same issue on the other side of the car.
It's my mates car and in his case it is just on the left cluster.
I think the problem is the crimping on that wire. Too tight.
Squashes the copper to such an extent that it reduces the cross sectional area of the cable
and therefore dramatically increases the resistance at that point and thus the heat damaging the cable and cluster.
So I decided to upgrade the brown ground wire to 20A cable and solder the connector to the cable instead
of crimping. Just on that cable. I then spliced that new cable to the original brown cable using a WAGO
splicer which is good for 32A.
Probably a little bit of overkill. A decent crimp on the original brown wire would probably be fine.
I just wanted to make sure it didn't happen again given it's my mate's car not mine.

Anyway. Thanks for the input.

 

[mattkh]

Very interesting.

 

[RayPooley]

One more thing. Don't try this DIY without the correct crimping tool for this type of connector.
You will only screw it up. It's not pricey. £11.00

 

[mattkh]

How reliable is the WAGO splicer in terms of amount of current going thru..?

 

[RayPooley]

How reliable is the WAGO splicer in terms of amount of current going thru..?

WAGOs are used in domestic and commercial electrical installations which typically operate under 240VAC. (120VAC in the US)
The one I used has a current carrying capacity of 32A and so can be used on lighting (6A) and socket circuits.
So there is no problem using them in an automotive environment.

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[RayPooley]

How reliable is the WAGO splicer in terms of amount of current going thru..?

I responded to this earlier with a link in it to some WGOs but it has been marked as waiting for mod approval so you can't see it.

So here it is again without the link.

WAGOs are used in domestic and commercial electrical installations which typically operate under 240VAC. (120VAC in the US)
The one I used has a current carrying capacity of 32A and so can be used on lighting (6A) and socket circuits.
So there is no problem using them in an automotive environment.